For many years the flight simulator training industry has been using various visual display techniques to provide the pilots with an out of the window view of the world.
The “simulated display industry” started out as a few specialist vendors supplying rigid model systems that had a mechanical “eye” that “flew” over a model board. The movement of this “magic eye” was controlled by the movement of the control column/side sticks in the cockpit and was a purely mechanical linkage system that provided the pilots with some form of terrain and visual representation.
With the growing availability of commercial computer graphics in the early 1970s it was not long before visual system manufacturers moved away from rigid models to some form of computer generated imagery (CGI).
This new computer generated “virtual” environment required some form of electronic display medium to transfer the software driven ‘virtual world’ to something that the pilot could view in the ‘real world’. In the early days this was a set of collimated monitor screens placed directly over each of the cockpit windows. This early simulation display system was the standard for the next decade.
In the early 1980's a company called Rediffusion Simulation Limited developed a unique display system that they christened WIDE (Wide-angled Infinity Display Equipment). This provided a cross cockpit out of the window view for the pilot and for the first time provided something approaching a real world scene. Since that time the word WIDE has been adopted by all visual system vendors as the generic term used to describe what is now the common standard in simulated display systems for aircraft simulators.
The first WIDE displays were all delivered with a 150 degree mirror, thus giving a continuous horizontal field of view of 150 degrees. This 150 WIDE as it is called by industry people is the most common and normal type of display delivered. A simplified schematic view of such a 150 degree display is depicted in FIG. 3.
Recently, the governing bodies of Europe have determined that the most effective training can only be accomplished by using a horizontal field of view of 180 degrees. For the past 4 years all training centers and airlines wishing to attain the highest certification level in Europe and Asia have had to use a 180 WIDE display. This common 180 standard became a pre-requisite for American training centers on Dec. 31, 2005.
This requirement has created a large upgrade market for the manufacturers of 180 mirrors to exploit. In the past few years a growing number of customers are having to remove their existing and perfectly useable 150 display mirrors and replace them with 180 display mirrors. The cost of replacing large state of the art optic display mirrors is very expensive and a complete system upgrade such as this usually costs more than $600,000 (US).
The existing 150 mirror cells that are removed are often sold for little more than the scrap value they bring to customers willing and able to train at lower certification levels.
After much analysis and investigation, the present inventors determined that the current approach of most vendors could be improved and provide an improvement in the geometric accuracy as viewed by the pilots. This analysis led the present inventors to investigate a new and better alternative to the current standard techniques for mirror installation used by other vendors.
The eventual result of this analysis was to develop a technique and subsequent set of tooling that very accurately replicated the standard curvature of the mirror cells in question. This curvature needed to be accurate in both horizontal and vertical directions in order to maintain accuracy and prevent undue distortions to the virtual image and also to prevent damage to the fragile Mylar™ material when being applied.